Crucibles for the melting and pouring of molten materials such as molten metals typically are provided with drain openings disposed in the bottom of the crucible to facilitate the pouring of the molten material from the crucible into a mold. However, heretofore difficulty has been encountered in devising suitable mechanisms for sealing the drain opening of the crucible while the charge material is being melted within the crucible and for selectively unsealing the drain opening to accommodate the pouring of the molten material from the crucible.
One apparatus which has been utilized in the past is a pouring rod which is provided with an distal end for being received in the drain opening to selectively seal the opening. In this regard, the pouring rod is inserted into an opening in the top of the crucible and the distal end is inserted into the drain opening in the crucible. The charge material to be melted is then loaded into the crucible and melted. When pouring of the molten material is desired the pouring rod is removed upwardly, thereby removing the distal end of the rod from the drain opening. However, the necessary presence of the pouring rod in the crucible during the loading of the charge material can obstruct the loading process and may limit the amount of charge material which can be loaded. Further, such pouring rods can be broken during the loading of the charge material, or during the melting process, causing a premature pouring or leaving the drain opening sealed with the distal end of the pouring rod.
Rupture disks are also commonly used to selectively seal the drain openings of crucibles. A rupture disk is received in the drain opening to seal the opening while the charge is loaded and the charge material is melted. When pouring is desired a pouring rod is inserted into the crucible and used to apply force to the disk such that it ruptures and opens the drain opening to the flow of molten material. An example of such a rupture disk apparatus is disclosed in U.S. Pat. No. 2,824,732. Whereas, the rupture disk obviates the inconvenience of having to leave the pouring rod in the crucible during the loading and melting process, premature pourings (cold pourings) are common due to premature fracturing or rupture of the disk, and failure to pour can result due to inadequate pouring force applied to a ruptured disk or resistance of the disks to fracture. Moreover, even where the disk ruptures in a timely manner, disk material can contaminate the molten material causing defects in the casting which is produced or otherwise compromising the molding process.
Other devices relating to the pouring of molten materials are disclosed in U.S. Pat. Nos. 4,799,650; 4,709,903; 4,601,415; and 3,651,825.
Therefore, it is an object of the present invention to provide a device for controlling the pouring of molten material from a crucible or other container for molten materials.
It is another object of the present invention to provide a device for controlling the pouring of molten materials from a crucible which effectively seals the drain opening in a crucible and avoid the premature pouring of the molten materials from the crucible.
Yet another object of the present invention is to provide a device for controlling the pouring of a molten material which does not contaminate the molten material or otherwise compromise the quality of the casting being produced.
Still another object of the present invention is to provide a device for controlling the pouring of a molten material which is reusable.